R8 heads Reloaded...

A6 All/ S6 All
#1

So for whatever reason I can’t post in the R8 heads thread norcan anyone else apperantly so I am starting it back up here.
Here is a link to the original thread

http://audirevolution.net/forum/index.php?topic=4427.0

I am basically theorizing that with a top swap and a crankshaft swap we would be able to frankenstine together a wet sump Lamborghini engine with all the fixins and same 1000-2000 hp potential. Although if the heads are that similar i think we really only need the cams and Crankshaft to make it work but i still like my Dream build but that Is a bit over kill. Thoughts?

#2

Great exciting topic

Here are the list of possible power adding parts you listed in the other thread. I removed the links as I think thats what caused issues for the html code

#3

I think this is a strong list.

The good news for us is that JHM has been sleeveing these aluminum blocks for a while starting with the much weaker 4.2 blocks so I think we have a good partner on this possible project. Sleeving these blocks is going to take some experience as we have less material to work with than the lambo blocks.

Im going to look into a few of the other parts you listed to make sure I can try to add something of strong substance to help get this formula off the ground

#4

Thanks, I really appreciate the help with the reasearch. I was jumping up and down when I discovered they use the same headgaskets. I think the potential scope for this platform is way beyond what most have realized. I hope my contribution may lead to other great builds and futhering the S6/S8 community.

#5

I agree. For years this platform was a pig with no chance of getting any serious recognition when it came to performance.

With the support of a real company in JHM and our excitement I think we can really turn the tide on the S6 and S8 V10 cars.

So here are a few thoughts.

The R8 heads I too found that gasket wise the heads should fit but I didn’t find anything that showed there was a difference in the valves. The big hang up that would for me take the R8 heads out of contention would be the camshafts. We can’t spin our motors to 8000+RPM so the R8 camshafts would have a power curve that would actually cost us power.

Im trying to look more into the 5.2 motors. From what I can see now the 5.2 S6 and S8 motors are like the 4.2 S5 motors. And the 5.2 R8 and Lambo motors are like the RS4 motors with extra block strength and reinforcements.

I really like the rods and piston idea but without the sleeved blocks it would IMHO be for nothing. I mentioned this in the other thread that JHM has been putting sleeves in the very brittle 4.2 motors for several years now and I think they have perfected the prossess. I think a built 5.2 motor would be awesome but you were right we would have to add a FI and the only forced induction kit that I have seen so far that really puts out big hp is the JHM vortech kit. The Vortech unit JHM uses is good for over 700hp and that is using one of the smaller vortech units.

I think right now the eairly stages of the v10 growth is starting to show itself. I don’t think the headers will be something that makes production I know CV is making a set for himself but I think headers or atleast the removal of the CATS will be a big pay off. I know both the 4.2 S4 and RS4 make big gains with removal of the cats. From what I have seen the 5.2 V10 can pick up almost 50whp with just a removal of the cats.

#6

Hopefully someone will put out a cat-removal option. I guess JHM would provide the tune. Going catless would be a great option for anyone whose cats fail down the line…

#7

Oh yes, I agree this build would not be for the faint of heart.

  1. Yes I believe that is correct I dont think the cams are well mated with our existing set up. If we were to use the R8 heads/cams we would also need the R8 Crankshaft. Timing chain sprocket on our cranks would not align with the R8 cams, they are timed differently. Also our split pin crankshaft would create delay that the cams just weren’t designed for.
  2. I proposed Sleeves for the purpose of durability that is inherently present in the R8/lambo RS4 style engine and lacking in ours also so some major power could be added.
  3. I really dont know that a whole top swap would be necessary. I can’t see much difference really in the heads beyond the cams. I am pretty sure I saw that the intake and exhaust valve ports are the same size as well. Also the R8’s have carbon build up issues just like us. So I say it would be for asthetics. Someone would really just want to have the lambo or R8 intake manifold to showoff. Especially going FI route the gains with better flow if any exist would be negated.
  4. I propose an entire R8 Crankshaft and Cam swap. This would allow for the correct timing between Crank and Cams. The Shared pin system of the R8/lambo is extremely strong especially with a aftermarket Crankshaft. As opposed to our split pin system (which I never really liked anyway, Looks inherently weak) Also add Forged rods/pistons for strength. And Bullet proofness.

Also looks like at least Saki can post in the other thread. lol

#8

Ok now your bringing back out the crazy in me. So ok now I can think on one other reason for doing the R8 top swap. The R8 exhaust Manifold are pretty much headers prefabbed and stamped. And actually if you do the cams and crank swap short headers are actually favorable to long tube headers. You get more power at high RPM’s with shorty style headers.

#9

Not sure that the R8 headers would fit because the R8 exhaust goes up to clear the transmission. Probably would need to cut the cats off and weld on flanges then have custom downpipes made if the shorty headers will clear the frame rails.

#10

The high pressure fuel pump camshaft followers are different between the S6/S8 and R8 V10. I am pretty sure that the heads are extremely similar otherwise except for a few weird things probably. For example, the exhaust valves are the same but I don’t see the intake valve part numbers easily to tell there. The valves spring and retainer upgrades from APR says that they fit both engines for whatever that is worth.

Then it would be vital to see the crankshaft main and rod journal sizes for bearings. Audi limits the bearing sizes drastically on a lot of their engines like the B6/7 S4s.

#11

Going over that right now. If it’s not Identical its Damn close. Haha

https://uploads.tapatalk-cdn.com/20170313/320c5fdf27f2ce1ad52a345ee34b7cc9.jpg
S6 on the left with the balance shaft R8 on right

#12

Well on the front side Crank bearing part notes say they are interchangeable. But it’s with the S6 4.0 tt :frowning:

https://uploads.tapatalk-cdn.com/20170313/0a932580a12f919b7d472da07b06d244.jpg

#13

Thrust washer is interchangeable with the R8 4.2 :frowning: so it will fit in the the main seal/Crank seal.

#14

Edit my post here not seeing any over lap about the intake valve after all would have to see what the difference is.

#15

Ok after searching all over I discovered that the Intake valves are indeed interchangeable as well.

https://uploads.tapatalk-cdn.com/20170313/9083f402d0254271beed70a62c17ccb7.jpg

#16

Doing some serious r&d research here I like it

#17

Both Cranks have a rod Journal diameter of 54mm.

#18

Rod bearings match but upon further review the Main bearing is listing size compatibility for the 4.0 Twin turbo S6. And the S6 Bearing is showing compatibility for 4.2 R8. The site wasn’t directly showing Dimensions so I found a site with exact dimensions. And Main bearing is 67mm for R8 crank and 65mm for the S6 crank. Which means you would have to lose 2 mm off the R8 Crankshaft diameter for it to fit the Main bearing Journals​. And off the end where it meets the thrust bearing. Lol you might actually score big if you find a used Lambo crank out of spec or just order the billet Crank -2mm of material off the diameter which is really removing only 1 mm of material.

#19

So I would say it’s not a direct bolt on as I had hoped but not out the realm Of possibility either. I think it would be a wonderful project. And I learned a lot about these engines. And similarities and difference’s.

#20

Thanks Jimmybones you put a bug in my ear and I really wanted to get to the bottom of this to be exactly sure this would be feasible. Just need a good chunk of cash to get started!